/******************************************************************************
 * Spine Runtimes License Agreement
 * Last updated September 24, 2021. Replaces all prior versions.
 *
 * Copyright (c) 2013-2021, Esoteric Software LLC
 *
 * Integration of the Spine Runtimes into software or otherwise creating
 * derivative works of the Spine Runtimes is permitted under the terms and
 * conditions of Section 2 of the Spine Editor License Agreement:
 * http://esotericsoftware.com/spine-editor-license
 *
 * Otherwise, it is permitted to integrate the Spine Runtimes into software
 * or otherwise create derivative works of the Spine Runtimes (collectively,
 * "Products"), provided that each user of the Products must obtain their own
 * Spine Editor license and redistribution of the Products in any form must
 * include this license and copyright notice.
 *
 * THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES,
 * BUSINESS INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *****************************************************************************/

import { Restorable, BlendMode } from "@esotericsoftware/spine-core";

export class ManagedWebGLRenderingContext {
	public canvas: HTMLCanvasElement | OffscreenCanvas;
	public gl: WebGLRenderingContext;
	private restorables = new Array<Restorable>();

	constructor (canvasOrContext: HTMLCanvasElement | WebGLRenderingContext, contextConfig: any = { alpha: "true" }) {
		if (!((canvasOrContext instanceof WebGLRenderingContext) || (typeof WebGL2RenderingContext !== 'undefined' && canvasOrContext instanceof WebGL2RenderingContext))) {
			let canvas: HTMLCanvasElement = canvasOrContext;
			this.gl = <WebGLRenderingContext>(canvas.getContext("webgl2", contextConfig) || canvas.getContext("webgl", contextConfig));
			this.canvas = canvas;
			canvas.addEventListener("webglcontextlost", (e: any) => {
				let event = <WebGLContextEvent>e;
				if (e) e.preventDefault();
			});
			canvas.addEventListener("webglcontextrestored", (e: any) => {
				for (let i = 0, n = this.restorables.length; i < n; i++)
					this.restorables[i].restore();
			});
		} else {
			this.gl = canvasOrContext;
			this.canvas = this.gl.canvas;
		}
	}

	addRestorable (restorable: Restorable) {
		this.restorables.push(restorable);
	}

	removeRestorable (restorable: Restorable) {
		let index = this.restorables.indexOf(restorable);
		if (index > -1) this.restorables.splice(index, 1);
	}
}

const ONE = 1;
const ONE_MINUS_SRC_COLOR = 0x0301;
const SRC_ALPHA = 0x0302;
const ONE_MINUS_SRC_ALPHA = 0x0303;
const ONE_MINUS_DST_ALPHA = 0x0305;
const DST_COLOR = 0x0306;

export class WebGLBlendModeConverter {
	static getDestGLBlendMode (blendMode: BlendMode) {
		switch (blendMode) {
			case BlendMode.Normal: return ONE_MINUS_SRC_ALPHA;
			case BlendMode.Additive: return ONE;
			case BlendMode.Multiply: return ONE_MINUS_SRC_ALPHA;
			case BlendMode.Screen: return ONE_MINUS_SRC_ALPHA;
			default: throw new Error("Unknown blend mode: " + blendMode);
		}
	}

	static getSourceColorGLBlendMode (blendMode: BlendMode, premultipliedAlpha: boolean = false) {
		switch (blendMode) {
			case BlendMode.Normal: return premultipliedAlpha ? ONE : SRC_ALPHA;
			case BlendMode.Additive: return premultipliedAlpha ? ONE : SRC_ALPHA;
			case BlendMode.Multiply: return DST_COLOR;
			case BlendMode.Screen: return ONE;
			default: throw new Error("Unknown blend mode: " + blendMode);
		}
	}

	static getSourceAlphaGLBlendMode (blendMode: BlendMode) {
		switch (blendMode) {
			case BlendMode.Normal: return ONE;
			case BlendMode.Additive: return ONE;
			case BlendMode.Multiply: return ONE_MINUS_SRC_ALPHA;
			case BlendMode.Screen: return ONE_MINUS_SRC_COLOR;
			default: throw new Error("Unknown blend mode: " + blendMode);
		}
	}
}